test/test_traversal.py

@@ -481,7 +481,7 @@ class TestTraversalHelpers:
             'id': 'name',
             'data': 'content',
             'url': 'url',
-        }, all, {subs_list_to_dict(lang=None)}]) == {
+        }, all, {subs_list_to_dict}]) == {
             'de': [{'url': 'https://example.com/subs/de.ass'}],
             'en': [{'data': 'content'}],
         }, 'subs with mandatory items missing should be filtered'
@@ -507,54 +507,6 @@ class TestTraversalHelpers:
             {'url': 'https://example.com/subs/en1', 'ext': 'ext'},
             {'url': 'https://example.com/subs/en2', 'ext': 'ext'},
         ]}, '`quality` key should sort subtitle list accordingly'
-        assert traverse_obj([
-            {'name': 'de', 'url': 'https://example.com/subs/de.ass'},
-            {'name': 'de'},
-            {'name': 'en', 'content': 'content'},
-            {'url': 'https://example.com/subs/en'},
-        ], [..., {
-            'id': 'name',
-            'url': 'url',
-            'data': 'content',
-        }, all, {subs_list_to_dict(lang='en')}]) == {
-            'de': [{'url': 'https://example.com/subs/de.ass'}],
-            'en': [
-                {'data': 'content'},
-                {'url': 'https://example.com/subs/en'},
-            ],
-        }, 'optionally provided lang should be used if no id available'
-        assert traverse_obj([
-            {'name': 1, 'url': 'https://example.com/subs/de1'},
-            {'name': {}, 'url': 'https://example.com/subs/de2'},
-            {'name': 'de', 'ext': 1, 'url': 'https://example.com/subs/de3'},
-            {'name': 'de', 'ext': {}, 'url': 'https://example.com/subs/de4'},
-        ], [..., {
-            'id': 'name',
-            'url': 'url',
-            'ext': 'ext',
-        }, all, {subs_list_to_dict(lang=None)}]) == {
-            'de': [
-                {'url': 'https://example.com/subs/de3'},
-                {'url': 'https://example.com/subs/de4'},
-            ],
-        }, 'non str types should be ignored for id and ext'
-        assert traverse_obj([
-            {'name': 1, 'url': 'https://example.com/subs/de1'},
-            {'name': {}, 'url': 'https://example.com/subs/de2'},
-            {'name': 'de', 'ext': 1, 'url': 'https://example.com/subs/de3'},
-            {'name': 'de', 'ext': {}, 'url': 'https://example.com/subs/de4'},
-        ], [..., {
-            'id': 'name',
-            'url': 'url',
-            'ext': 'ext',
-        }, all, {subs_list_to_dict(lang='de')}]) == {
-            'de': [
-                {'url': 'https://example.com/subs/de1'},
-                {'url': 'https://example.com/subs/de2'},
-                {'url': 'https://example.com/subs/de3'},
-                {'url': 'https://example.com/subs/de4'},
-            ],
-        }, 'non str types should be replaced by default id'
 
     def test_trim_str(self):
         with pytest.raises(TypeError):
@@ -573,7 +525,7 @@ class TestTraversalHelpers:
     def test_unpack(self):
         assert unpack(lambda *x: ''.join(map(str, x)))([1, 2, 3]) == '123'
         assert unpack(join_nonempty)([1, 2, 3]) == '1-2-3'
-        assert unpack(join_nonempty, delim=' ')([1, 2, 3]) == '1 2 3'
+        assert unpack(join_nonempty(delim=' '))([1, 2, 3]) == '1 2 3'
         with pytest.raises(TypeError):
             unpack(join_nonempty)()
         with pytest.raises(TypeError):

test/test_utils.py

@@ -72,6 +72,7 @@ from yt_dlp.utils import (
     intlist_to_bytes,
     iri_to_uri,
     is_html,
+    join_nonempty,
     js_to_json,
     limit_length,
     locked_file,
@@ -2157,6 +2158,10 @@ Line 1
         assert int_or_none(v=10) == 10, 'keyword passed positional should call function'
         assert int_or_none(scale=0.1)(10) == 100, 'call after partial application should call the function'
 
+        assert callable(join_nonempty(delim=', ')), 'varargs positional should apply partially'
+        assert callable(join_nonempty()), 'varargs positional should apply partially'
+        assert join_nonempty(None, delim=', ') == '', 'passed varargs should call the function'
+
 
 if __name__ == '__main__':
     unittest.main()

yt_dlp/extractor/common.py

@@ -3767,7 +3767,7 @@ class InfoExtractor:
         """ Merge subtitle dictionaries, language by language. """
         if target is None:
             target = {}
-        for d in filter(None, dicts):
+        for d in dicts:
             for lang, subs in d.items():
                 target[lang] = cls._merge_subtitle_items(target.get(lang, []), subs)
         return target

yt_dlp/extractor/rutube.py

@@ -13,10 +13,7 @@ from ..utils import (
     unified_timestamp,
     url_or_none,
 )
-from ..utils.traversal import (
+from ..utils.traversal import traverse_obj
-    subs_list_to_dict,
-    traverse_obj,
-)
 
 
 class RutubeBaseIE(InfoExtractor):
@@ -95,11 +92,11 @@ class RutubeBaseIE(InfoExtractor):
                 hls_url, video_id, 'mp4', fatal=False, m3u8_id='hls')
             formats.extend(fmts)
             self._merge_subtitles(subs, target=subtitles)
-        self._merge_subtitles(traverse_obj(options, ('captions', ..., {
+        for caption in traverse_obj(options, ('captions', lambda _, v: url_or_none(v['file']))):
-            'id': 'code',
+            subtitles.setdefault(caption.get('code') or 'ru', []).append({
-            'url': 'file',
+                'url': caption['file'],
-            'name': ('langTitle', {str}),
+                'name': caption.get('langTitle'),
-        }, all, {subs_list_to_dict(lang='ru')})), target=subtitles)
+            })
         return formats, subtitles
 
     def _download_and_extract_formats_and_subtitles(self, video_id, query=None):

yt_dlp/utils/_utils.py

@@ -216,7 +216,7 @@ def partial_application(func):
     sig = inspect.signature(func)
     required_args = [
         param.name for param in sig.parameters.values()
-        if param.kind in (inspect.Parameter.POSITIONAL_ONLY, inspect.Parameter.POSITIONAL_OR_KEYWORD)
+        if param.kind in (inspect.Parameter.POSITIONAL_ONLY, inspect.Parameter.POSITIONAL_OR_KEYWORD, inspect.Parameter.VAR_POSITIONAL)
         if param.default is inspect.Parameter.empty
     ]
 
@@ -4837,6 +4837,7 @@ def number_of_digits(number):
     return len('%d' % number)
 
 
+@partial_application
 def join_nonempty(*values, delim='-', from_dict=None):
     if from_dict is not None:
         values = (traversal.traverse_obj(from_dict, variadic(v)) for v in values)

yt_dlp/utils/traversal.py

@@ -332,14 +332,14 @@ class _RequiredError(ExtractorError):
 
 
 @typing.overload
-def subs_list_to_dict(*, lang: str | None = 'und', ext: str | None = None) -> collections.abc.Callable[[list[dict]], dict[str, list[dict]]]: ...
+def subs_list_to_dict(*, ext: str | None = None) -> collections.abc.Callable[[list[dict]], dict[str, list[dict]]]: ...
 
 
 @typing.overload
-def subs_list_to_dict(subs: list[dict] | None, /, *, lang: str | None = 'und', ext: str | None = None) -> dict[str, list[dict]]: ...
+def subs_list_to_dict(subs: list[dict] | None, /, *, ext: str | None = None) -> dict[str, list[dict]]: ...
 
 
-def subs_list_to_dict(subs: list[dict] | None = None, /, *, lang='und', ext=None):
+def subs_list_to_dict(subs: list[dict] | None = None, /, *, ext=None):
     """
     Convert subtitles from a traversal into a subtitle dict.
     The path should have an `all` immediately before this function.
@@ -352,7 +352,7 @@ def subs_list_to_dict(subs: list[dict] | None = None, /, *, lang='und', ext=None
     `quality`  The sort order for each subtitle
     """
     if subs is None:
-        return functools.partial(subs_list_to_dict, lang=lang, ext=ext)
+        return functools.partial(subs_list_to_dict, ext=ext)
 
     result = collections.defaultdict(list)
 
@@ -360,15 +360,9 @@ def subs_list_to_dict(subs: list[dict] | None = None, /, *, lang='und', ext=None
         if not url_or_none(sub.get('url')) and not sub.get('data'):
             continue
         sub_id = sub.pop('id', None)
-        if not isinstance(sub_id, str):
+        if sub_id is None:
-            if not lang:
             continue
-            sub_id = lang
+        if ext is not None and not sub.get('ext'):
-        sub_ext = sub.get('ext')
-        if not isinstance(sub_ext, str):
-            if not ext:
-                sub.pop('ext', None)
-            else:
             sub['ext'] = ext
         result[sub_id].append(sub)
     result = dict(result)
@@ -458,9 +452,9 @@ def trim_str(*, start=None, end=None):
     return trim
 
 
-def unpack(func, **kwargs):
+def unpack(func):
     @functools.wraps(func)
-    def inner(items):
+    def inner(items, **kwargs):
         return func(*items, **kwargs)
 
     return inner